The invention relates to a device for controlling an internal combustion engine. In devices for controlling an internal combustion engine of a motor vehicle, particularly for controlling the ignition and the like, it is known to use sensor systems for detecting an angular position of a shaft of the internal combustion engine, particularly the crankshaft or the camshaft.
Such systems are constructed e.g. as segment systems in and transmitter disks rotate with the shaft, which are provided at their circumference with a plurality of segments, i.e. elongated marked areas, proportional to the number of cylinders of the internal combustion engine. In the detection of the angular position of the crankshaft, the number of segments amounts to one half of the number of cylinders. In the detection of the angular position of the camshaft the number of segments is identical to the number of cylinders, since the crankshaft rotates at twice the speed of the camshaft, as is known. Every segment is assigned to a cylinder (n) of the internal combustion engine (two cylinders in the detection of the angular position of the crankshaft), and every ignition process is controlled as a function of the passage of a respective segment. In a stationary receiving element, the leading edge of the segment is detected, and the control processes for the internal combustion engine are triggered by a suitable time control over the entire length of the segment. On the other hand, segment systems with segments of equal dimensions have the disadvantage that an assignment, which is sufficient for a high-voltage distribution without the use of a distributor or for a dual-circuit (e.g. eight-cylinder engine) high-voltage distribution, is not possible.
In addition, segment systems are known in which individual segments are divided by a number of teeth and tooth spaces and the signals produced by the teeth and tooth spaces, respectively, are fed to a control circuit. In so doing, the angular position of the shaft is determined by counting the passing teeth and tooth spaces, respectively. This method is costly and requires an additional counting device.
In addition, if only a single tooth space is formed in a segment, there is the risk that the additional trailing edge will trigger an additional ignition.
In all devices mentioned here, at least one revolution is required when starting the internal combustion engine in order to detect an accurate assignment of the marking.